NCBI Summary:
At the nuclear envelope, the nuclear lamina and heterochromatin are adjacent to the inner nuclear membrane. The protein encoded by this gene binds DNA and is a component of heterochromatin. This protein also can bind lamin B receptor, an integral membrane protein found in the inner nuclear membrane. The dual binding functions of the encoded protein may explain the association of heterochromatin with the inner nuclear membrane. Two transcript variants encoding the same protein but differing in the 5' UTR, have been found for this gene.
General function
Chromosome organization, DNA binding
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Cellular localization
Nuclear
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Ovarian function
Early embryo development
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Expression of Polycomb-group genes in human ovarian follicles, oocytes and preimplantation embryos Hinkins M, et al .
Mammalian oocytes possess unique properties with respect to their ability to regulate and reprogram chromatin structure and epigenetic information. Proteins containing the conserved chromodomain motif that is common to the Polycomb-group (Pc-G) proteins and the heterochromatin-associated protein HP1, play essential roles in these processes and more specifically, in X-chromosome inactivation in female zygotes and extra-embryonic tissues and in the regulation of genomic imprinting. To characterize the potential role of these proteins in the regulation of epigenetic events during early human development, we utilized a degenerate PCR priming assay to assess the expression of mRNAs of chromodomain proteins in cDNA samples derived from the human female germline and preimplantation embryos. Expression of mRNAs of HP1 genes was observed in ovarian follicles, (HP1 (HSalpha), HP1 (HSbeta), HP1 (HSgamma)), mature oocytes (HP1 (HSalpha), HP1 (HSbeta)), cleavage stage preimplantation embryos (HP1 (HSalpha), HP1 (HSbeta), HP1 (HSgamma)) and blastocysts (HP1 (HSalpha), HP1 (HSgamma)). Transcripts for three Pc-G genes, which are essential for early mammalian development (Yin Yang 1 (YY1), Enhancer of Zeste-2 (EZH2) and Embryonic Ectoderm Development (EED)) and that are essential for the regulation of X-inactivation and certain imprinted genes (EED) were revealed by gene-specific-PCR expression analysis of human ovarian follicles, oocytes and preimplantation embryos. YY1 and EZH2 transcripts were additionally detected in metaphase II oocytes.
Expression regulated by
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Ovarian localization
Oocyte
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Epigenetic Characteristics of Paternal Chromatin in Interspecies Zygotes. Barnetova I et al. Both the sperm and oocyte are terminally differentiated cells, but within a very short post-fertilization period, their genomes are converted into a totipotent zygote. The process of this transformation has been studied in a number of mammals as well as in the pig, for which very inconsistent results have been published. To clarify these inconsistencies, we have used the interspecies intracytoplasmic sperm injection technique for embryo production and subsequent paternal genome remodeling evaluation. First, we injected boar sperm heads into ovulated and in vitro matured mouse oocytes. The boar spermatozoa consistently decondense in ovulated oocytes and form fully developed pronuclei with demethylated DNA (5-methylcytosine; 5-MeC). Additional labeling against other histone modifications (H3/K9 dimethylation, H3/K4 trimethylation) and HP1 (Heterochromatin Protein 1) revealed similarity to those changes that are typical for natural mouse zygotes. On the other hand, no decondensation and formation of male pronuclei were observed, in spite of obvious oocyte activation, in in vitro matured oocytes. For this reason, we have evaluated the reprogramming parameters of in vitro matured mouse oocytes in more detail. In mouse zygotes (intraspecific), both pronuclei were consistently formed, but no sperm head chromatin demethylation was detected after 5-MeC labeling. Our observations suggest that porcine sperm heads are capable of undergoing active demethylation in in vivo matured mouse oocytes. On the other hand, in vitro matured oocytes possess much lower sperm remodeling capabilities.